Biological stimulants are often used to enhance the natural attenuation of environmental contaminants. Bioremediation products are commercially used to attenuate such contaminants as fuel hydrocarbon constituents and organic solvents that may be biologically transformed or immobilized under aerobic conditions. The dissolved oxygen released from such products transforms/immobilizes the contaminants.
For this reason, a slow dissolved oxygen release is preferred to increase contact with the contaminants dissolved in groundwater or adsorbed onto the formation matrix. A fast release is ineffective when trying to remove the contaminants. For example, magnesium/calcium peroxide is a potential stimulant for contaminant attenuation. However, upon hydration these peroxides tend to disassociate rapidly. In fact, magnesium/calcium peroxide can release their entire dissolved oxygen load within a few weeks of hydration. For optimum use, such stimulants must release dissolved oxygen slowly over a longer period of time, on the order of months and not weeks.
There are other compounds, such as MgO2, that slowly release oxygen when chemically bonded with phosphate. This release of oxygen is a chemical process. Again, if the oxygen is released too fast, the compound is useless as a bioremediation product. While chemically-bonded products can solve the time-releasing problem, such compounds can be costly to manufacture and use in large amounts.
U.S. Pat. No. 6,569,342, issued to Willuweit et al. on May 27, 2003, discloses a method for treating water wherein an alkaline earth metal peroxide is brought into contact with water to immobilize phosphates and heavy metals except manganese and iron. This method accomplishes the task by rapidly changing the pH, counteracting the oxygen deficit. This does not result in the magnesium peroxide that Willuweit says may be substituted for calcium peroxide to disassociate to dissolved oxygen at a slower rate than it would be if magnesium peroxide were by itself Willuweit et al. also suggests that bentonites may be added to his mixture but provides no reason why this might be desirable or any suggestion as to what % weight of bentonites are suggested for a given weight of alkaline earth metal peroxide. Further, Willuweit et al. teaches that, for practical reasons, the bentonites if added should be compacted and used as granules, pellets or tablets.
Therefore, what is needed is a blend to release dissolved oxygen that can be manufactured without using a chemical process. A blend for use as a bioremediation product that releases dissolved oxygen slowly over a long time frame is also needed. Such a blend that satisfies the time frame demands at a low cost is not commercial available.